ECLIPSE OF THE SUN, APRIL 25, 1865. 
Paris, June 23, 1865. 
Sir: [have the honor to address to you the copy of a very interesting letter 
which I have received from a distinguished savant, M. le Baron de Prados, of 
Rio de Janeiro, on the total eclipse of the sun of the 25th of April last. 
It appears to me important that this letter should be published, for we need 
the preservation of accounts of all the principal eclipses in order to complete the 
theory of the physical constitution of the sun. I request, therefore, that you 
will cause it to be published, if possible, in some of the works issued by the 
Smithsonian Institution. 
Be pleased, sir, to accept the assurance of the respectful consideration of your 
humble servant, 
EMM. LIAIS, 
Astronomer of the Observatory of Paris, 
Mission Scientifique, 56 Rue de Belle-Chatte. 
Professor HENRY, 
Secretary of the Smithsonian Institution. 
On the eclipse of the sun, April 25, 1865. 
{Extract of a letter from M. le‘Baron de Prados to M. Liais, dated April 26.] 
In pursuance of your indications I repaired to Rio de Janeiro some days be- 
fore the opening of the Chambers,* that I might be able to observe the eclipse 
of the 25th instant. Unfortunately, the sky remained overclouded up to the 
time of the first contact. When the sun could be observed, the shadow of the 
moon had already invaded its disk, so that the first contact was lost. The last 
exterior contact, the only one which I could observe with any exactness, took 
place, according to the observers who were present at the imperial opservatory, 
myself being among them, at 114. 54m. 5s. Being at the great meridian re- 
fractor, which had been removed in order to be directed upon the sun, I was ena- 
bled to follow those physical details which there was an opportunity of observing. 
The eclipse was not absolutely total at the observatory. A thread of light 
which, at the height of the phenomenon, took the form of a chaplet, perhaps 
prevented the observation of all the particulars of the corona. This last showed 
itself, however, for some moments in all its splendor. The following are the 
special cireumstances which I was able to remark during the short duration of 
the phenomenon : 
At the moment when the luminous thread assumed the chaplet form, the 
*M. Baron de Prados is president of the Corps Legislatif of Brazil. He resides at Barba- 
cena, where he has caused to be constructed at his own expense, and maintains, a large hos- 
pital for the poor. He studied medicine at Paris when young, and conducts the above es- 
iablishment himself. The Chambers opened eight days after the eclipse, which explains the 
first phrases of the letter. 
